The invention relates to a pane with an electrical connection element, an economical and environmentally friendly method for its production, and its use.
The invention relates in particular to a pane with an electrical connection element for motor vehicles with electrically conductive structures such as, for instance, heating conductors or antenna conductors. The electrically conductive structures are customarily connected to the onboard electrical system via soldered-on electrical connection elements. Due to different coefficients of thermal expansion of the materials used, mechanical stresses occur during production and operation that strain the panes and can cause breakage of the pane.
Lead-containing solders have high ductility that can compensate the mechanical stresses occurring between an electrical connection element and the pane by plastic deformation. However, because of the End of Life Vehicles Directive 2000/53/EC, lead-containing solders have to be replaced by lead-free solders within the EC. The directive is referred to, in summary, by the acronym ELV (End of Life Vehicles). Its objective is to ban extremely problematic components from products resulting from the massive increase in disposable electronics. The substances affected are lead, mercury, and cadmium. This relates, among other things, to the implementation of lead-free soldering materials in electrical applications on glass and the introduction of corresponding replacement products.
A number of electrical connection elements for leadfree soldering to electrically conductive structures have been proposed. Reference is made, by way of example, to the documents US 20070224842 A1, EP 1942703 A2, WO 2007110610 A1, EP 1488972 A1, and EP 2365730 A1. The shape of the connection element, on the one hand, and the material of the connection element, on the other, assume critical significance with regard to the avoidance of thermal stresses.